1. Field of the Invention
The present invention generally relates to security systems and, more particularly, to an apparatus and method for screening automobiles, including light trucks and vans, for concealed persons, explosives, contraband and other materials.
2. Description of the Prior Art
Motor vehicles such as automobiles, light trucks and vans have been used in many prohibited activities involving the transportation of persons or contraband such as in robberies and smuggling. More recently, such vehicles have also been utilized in terrorist activities such as in assaults and what has come to be known as car bombings in which a substantial amount of explosive material is concealed in the motor vehicle and the motor vehicle parked in a particular location and the explosives detonated, either with a timer or a remote control, such as a radio link.
Particularly in this latter case, the location chosen for a car bomb will often be a relatively crowded public place with a high volume of pedestrian and vehicular traffic. Public events will often be chosen where a large number of vehicles will be parked in an area with limited access such as parking lots. To gain closer access to crowded areas, vans and light trucks may be made to appear to be service vehicles having a legitimate reason for such access.
Given the probability of high traffic volume, there is a need to be able to screen vehicles for the presence of explosives at points of vehicular access to areas such as parking lots, service areas and the like. At the same time, however, such traffic must not be seriously impeded, particularly at scheduled events where admission fees are charged. The likelihood of public inconvenience in such circumstances can easily cause a major adverse effect on the commercial success of such events, particularly when the screening procedure is highly visible to the public. In this latter case, the public may infer that from such activities that terrorist activity is considered particularly likely or even that an actual threat of terrorism may have occurred.
It should be understood that, in some circumstances, high visibility of inspection or screening procedures may be considered desirable as a deterrent to prohibited activities such as terrorism. However, prior methods leave little flexibility to reduce visibility, should reduced visibility be desired and deleterious effects of visibility of inspection and screening methods on attendance at commercial events could not be avoided.
In this regard, the manual search of a suspect vehicle is often of high visibility. If a vehicle is suspected of carrying explosives or contraband, known detection techniques are often incapable of indicating any location within the vehicle where such materials are likely to be concealed, increasing the thoroughness of the search required and the visibility thereof to members of the public. The duration of such a thorough search may also make particular known screening systems objectionable even for relatively small numbers of false-positive detections.
To date, screening procedures for explosives carried in vehicles has concentrated on the constituent materials of the explosives, which commonly contain a high percentage of nitrates. Such material detecting procedures involve isolating the vehicle, sampling the air in or around it and analyzing the sampled air for nitrates or taking a surface sample of material around the hood, trunk or door areas of the vehicle for similar analysis for nitrate residues. These procedures take several minutes and are therefore not compatible with high volume traffic situations. The use of trained dogs for more rapid detection of explosive materials has been found to be insufficiently accurate as well as being highly visible and often intrusive.
Other techniques for detecting explosives and other items such as weapons and contraband have also focussed on highly advanced technology such as X-rays, so-called prompt gamma neutron analysis and the like. These techniques usually involve large and very expensive equipment and review of the results by highly trained personnel. Nevertheless, such techniques are subject to a high error or false-positive rate since the shape of any container for explosives or other items is substantially arbitrary and may be disguised to appear as other articles which would be expected to be present such as tires, drive shafts, hollow body panels and the like. The speed of detection is also generally insufficient to many situations which commonly occur.
The possibility of terrorist activities at particular events and the expense of any type of detection equipment also makes it desirable that the detection equipment be portable. Due to the size of motor vehicles to be screened, this is often not possible or at least very costly for X-ray equipment or the like. The need to isolate vehicles for nitrate analysis detection techniques also generally requires at least some sort of barriers or substantial size and weight. Therefore, prior detection techniques have required substantial costs to be incurred when equipment must be moved to screen vehicles at different events. The alternative is, of course, to provide a greater number of detection systems, often at great cost and inefficiency of utilization of such equipment.
Therefore, a need exists for a screening technique which is of reduced cost, improved portability, reduced visibility and of high accuracy. A need also exists for a screening technique for motor vehicles which will assist in the search of suspect vehicles by providing an indication of the location where contraband or explosives may be concealed therein.